JP2001337147A - Magnetic field sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of an input offset voltage of a magnetic field sensor by means of a small-sized circuit. SOLUTION: In a first timing, a power source voltage is impressed between terminals A, A' of a hole element 1, a voltage Vh between terminals B, B' is inputted to a voltage amplifier 3, and a voltage V1=β(Vh+Voff) proportional to the sum of the voltage Vh and an input offset voltage Voff of the voltage amplifier 3 is outputted. In addition, a switch 5 is closed and a capacitor 4 is charged to the voltage V1. In a second timing, the power source voltage is impressed between the terminals B, B' of the hole element 1, a voltage -Vh' between the terminals A, A' is inputted to the voltage amplifier 30, so that a polarity opposite to that of the first timing is provided, and a voltage V2=β(-Vh'+Voff) is outputted. The switch 5 is opened, a detection voltage V=V2-V1=-β(Vh+Vh') from canceling the input offset voltage is outputted from output terminals 6, 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a Hall element and an amplifier for amplifying an output voltage of the Hall element, detects a magnetic field at a place where the Hall element is installed, and outputs a signal corresponding to the strength of the detected magnetic field. The present invention relates to a magnetic field sensor that outputs

[0002]

2. Description of the Related Art A typical magnetic field sensor constituted by a bipolar IC or a CMOS IC includes a Hall element for outputting an output voltage proportional to the strength of a magnetic field, an amplifier for amplifying an output voltage of the Hall element, and an output of the amplifier. A comparator for comparing the voltage with a predetermined reference voltage and outputting a comparison result, wherein a binary value (0 or 1, a high level or a high level) is determined according to whether the magnetic field at the place where the magnetic field sensor is installed is stronger or weaker than a certain reference. (Low level) signal.

Another magnetic field sensor includes a similar Hall element and an amplifier, and outputs an analog signal based on the output of the amplifier.

In order to obtain an accurate comparison result or an analog signal corresponding to the strength of a magnetic field, any of the magnetic field sensors described above suppresses an offset signal component included in a signal output from an amplifier, It is necessary to reduce the variation in the signal output from the amplifier for each magnetic field sensor (product). The main causes of the offset signal component are an offset signal component (hereinafter referred to as an “element offset voltage”) included in the output voltage of the Hall element and an offset signal present at an input terminal of an amplifier (generally, a differential amplifier). Signal component (hereinafter referred to as “input offset voltage”). The former is caused by stress or the like that the Hall element body receives from the package. The latter is caused by variations in characteristics of elements constituting an input circuit of the amplifier. Hereinafter, a conventional technique for suppressing these offset signal components will be described. (Prior Art 1) A technique for reducing the influence of the element offset voltage is described in, for example, US Pat.
No. 7,150 is known. That is, a Hall element used in a magnetic field sensor generally has four terminals A and A ′, as in a Hall element 61 shown in FIG.
-It is formed in a plate shape having a geometrically equivalent shape with respect to BB. Here, the geometrically equivalent shape refers to the shape in the state shown in FIG. 2 like the rectangular Hall element 61 shown in FIG.
Is rotated to match BB ′). Such a Hall element 6
When a power supply voltage is applied between terminals A and A '
The effective signal component corresponding to the strength of the magnetic field is in phase between the voltage generated between B ′ and the voltage generated between terminals A and A ′ when a power supply voltage is applied between terminals BB and B ′. The offset voltage has the opposite phase. Therefore, a power supply voltage from a power supply (not shown) is sequentially applied between the terminals A and A 'and between the terminals BB and B' of the Hall element 61 via the switch circuit 62, and between the terminals B and B 'and between the terminals A and B'. The voltage between A 'is taken out as the element output voltage, and by taking the average of these two element output voltages, the element offset voltage can be canceled to obtain only the effective signal component. (Prior Art 2) A magnetic field sensor disclosed in Japanese Patent Application Laid-Open No. 8-201491 is known as a magnetic field sensor capable of reducing the influence of an element offset voltage and also reducing the influence of an input offset voltage generated in an amplifier. I have. As shown in FIG. 7, the magnetic field sensor includes a Hall element 61, a switch circuit 62, and a voltage-current conversion amplifier 64.
65, capacitors 66 and 67 as storage elements, switches 68 and 69, and a resistor 70 are provided. The voltage-current conversion amplifiers 64 and 65 have a high input / output impedance, and convert an input voltage into a current and output the current. The switch 68 shown in FIG.
The switch 69 closes in response to the pulse of the second phase in the second phase signal (b) while closing in response to the pulse of the first phase in the first phase signal (a) shown in the timing chart of FIG. It has become. In addition, according to the pulse of the first phase and the pulse of the second phase, the switch circuit 62 includes a power supply and a voltage-current conversion amplifier 64 (not shown) and terminals A and The connection with A ', BB, and B' is switched. That is, this magnetic field sensor outputs a voltage corresponding to the strength of the magnetic field by the two-step operation of the first and second timings corresponding to the pulses of the first and second phases as described below. It has become.

First, at a first timing, a power supply voltage is applied between the terminals A and A ′ of the Hall element 61 and a voltage V between the terminals BB and B ′ via the switch circuit 62.
h is input to the voltage-current conversion amplifier 64. Therefore, as shown in the following equation (1), the voltage Vh between the terminals BB and the input offset voltage V
The current IOUT1 is output in proportion to the sum of the current IOFF and the current IOUT1.

IOUT1 = α (Vh + Voff) (1) where α is the transconductance of the voltage-to-current conversion amplifier 64 (proportional constant which is a conversion coefficient from voltage to current), V
h is the voltage between the terminals B and B ′ of the Hall element 61 (the input voltage to the voltage-current conversion amplifier 64), and Voff is the input offset voltage of the voltage-current conversion amplifier 64.

At the first timing, while the switches 68 are closed and the switches 69 are opened, the current IOUT1 output from the voltage-to-current conversion amplifier 64 flows into the capacitors 66 and 67.
The capacitors 66 and 67 are charged to generate a charging voltage. The difference voltage between the charging voltages of the capacitors 66 and 67 is input to the voltage-to-current conversion amplifier 65, and is output from the voltage-to-current conversion amplifier 65 in a magnitude proportional to the difference voltage between the charging voltages. Outputs a current in the reverse direction (direction for canceling the charging current to the capacitors 66 and 67). This current increases as the charging of the capacitors 66 and 67 progresses, and eventually the voltage-current conversion amplifier 64
, Ie, all the currents output from the voltage-to-current conversion amplifier 64 are
, The charging current to the capacitors 66 and 67 becomes 0, and the capacitors 66 and 67 are in an equilibrium state. At this time, the current IOUT2 output from the voltage-current conversion amplifier 65
Is a current having the opposite polarity and the same absolute value as IOUT1 as in the following equation (2).

IOUT2 = −α (Vh + Voff) (2) Next, at a second timing, the switches 68 and 68 are opened and the switches 69 and 69 are closed. Therefore, the charges stored in the capacitors 66 and 67 are held as they are (therefore, the charging voltage is also maintained), and the voltage-current conversion amplifier 65
Keeps the output current IOUT2 flowing. At the second timing, the power supply voltage is applied between the terminals B and B 'of the Hall element 61 via the switch circuit 62, and the terminal A is turned to the opposite polarity to the first timing. The voltage −Vh ′ between A ′ is a voltage-current conversion amplifier 6
4 is input. Therefore, the current IOUT3 shown in the following equation (3) is output from the voltage-current conversion amplifier 64.

IOUT3 = α (−Vh ′ + Voff) (3) That is, since the influence of the input offset voltage Voff is the same as the first timing regardless of the polarity of the input voltage, the output current IOUT3 of the voltage-current conversion amplifier 64 is , First
-V between the terminals A and A 'having the opposite polarity to the timing
The current is proportional to the sum of h ′ and the input offset voltage Voff.

The output current I of the voltage-to-current conversion amplifier 64 is
OUT3 and the output current IOUT of the voltage-current conversion amplifier 65
2 is connected to the resistor 7 via the switches 69
0, and the voltage across the resistor 70 becomes the output voltage V of the magnetic field sensor. Therefore, as shown in the following equation (4), an output voltage V in which the influence of the input offset voltage Voff is canceled is obtained. Also, at this output voltage V,
Since the output voltages Vh and Vh ′ from the Hall element 61 at the first and second timings are added,
As described in U.S. Pat. No. 4,037,150, the influence of the element offset voltage is also canceled.

V = (IOUT2 + IOUT3) × R = −α (Vh + Vh ′) × R (4) (Prior art 3) Further, as another magnetic field sensor capable of reducing the effects of the element offset voltage and the input offset voltage, The following are also known. As shown in FIG. 9, this magnetic field sensor includes a Hall element 61, a switch circuit 62, a voltage amplifier 71, capacitors 72 and 73 having the same capacity as a storage element, and a switch 74.
To 76 are provided. Switch 74
To 76 are closed in accordance with the first to third phase pulses in the first to third phase signals (a) to (c) shown in FIG. 10, respectively. That is, the magnetic field sensor outputs a voltage corresponding to the strength of the magnetic field by the three-step operation of the first to third timings corresponding to the pulses of the first to third phases as described below. It has become.

First, at the first timing, a power supply voltage is applied between the terminals A and A 'of the Hall element 61 through the switch circuit 62 and the terminals BB and Is input to the voltage amplifier 71. Therefore, assuming that the voltage amplification factor of the voltage amplifier 71 is β, the voltage Vh between the terminals B and B ′ and the input offset voltage Vo are obtained from the voltage amplifier 71 as shown in the following equation (5).
A voltage V1 proportional to the sum of ff and ff is output.

V1 = β (Vh + Voff) (5) At this first timing, the switches 74
Is closed while the switches 75, 75, 76 and 76 are opened, so that the capacitor 72 is charged to the voltage V1.

Next, at the second timing, a power supply voltage is applied between the terminals B and B 'of the Hall element 61 via the switch circuit 62, and the polarity is opposite to that of the first timing. The voltage −Vh ′ between the terminals A and A ′ is input to the voltage amplifier 71. Therefore, the voltage amplifier 71
Outputs a voltage V2 represented by the following equation (6).

V2 = β (−Vh ′ + Voff) (6) That is, (the voltage-current conversion amplifier 6
4) input offset voltage V
Since the effect of off is the same as the first timing regardless of the polarity of the input voltage, the output voltage V2 of the voltage amplifier 71 is equal to the voltage −V between the terminals A and A ′ having the opposite polarity to the first timing.
It becomes a voltage proportional to the sum of h ′ and the input offset voltage Voff. At the second timing, the switches 75, 75 are closed while the switches 74, 74, 76,
By opening the capacitor 76, the capacitor 73 is connected to the voltage V2.
Is charged.

Next, at the third timing, the switch 7
4.74.75.75 opens while switches 76.76 open.
Is closed, and the capacitors 72 and 73 are connected to the terminal 7
2a and the terminal 73b are connected in parallel so that the terminal 72b and the terminal 73a are connected respectively. Therefore, since the capacitances of the capacitors 72 and 73 are equal to each other as described above, the voltage V between both ends of the capacitors 72 and 73 is an average voltage of -V1 and V2 as shown in the following equation (7).

V = (− V1 + V2) / 2 = −β (Vh + Vh ′) / 2 (8) Therefore, similarly to the above-described related art 1, the influence of the input offset voltage Voff and the influence of the element offset voltage are offset. The obtained output voltage V is obtained.

[0018]

However, the conventional magnetic field sensor has a problem that it is difficult to reduce the circuit scale for suppressing the influence of the input offset voltage. That is, the conventional technique 2 requires two voltage-current conversion amplifiers, two capacitors, and four switches, and the conventional technique 3 requires one capacitor but two capacitors and six switches. I need. Moreover, the voltage-current conversion amplifier and the voltage amplifier are two-output amplifiers having a non-inverted output (positive output) and an inverted output (negative output). Such an amplifier has a large number of elements constituting an output section. In addition, a large chip area is occupied when forming an IC.

In recent years, a magnetic field sensor has been used in a battery-operated device such as a mobile phone.
Reduction of the current consumption of the magnetic field sensor has also become an important technical issue. As a means used to reduce current consumption, it is common to employ an intermittent operation in which current consumption is reduced to zero for a certain period of time using a counter or the like.

However, depending on the set using the magnetic field sensor, the time during which the sensor operation can be stopped is limited, and the number of steps in which one detection operation can be realized becomes a problem. Specifically, in the first conventional example, the first and second
The magnetic field is measured in two steps of the phase of. In the second conventional example, the magnetic field is measured in three steps of the first to third phases.

In view of the above, the present invention suppresses the influence of an offset signal component (variation) contained in the output of a magnetic field sensor, particularly the influence of an input offset voltage generated in an amplifier, and can detect a magnetic field with high accuracy. Another object of the present invention is to reduce the circuit scale and reduce the manufacturing cost. Another object is to reduce power consumption by reducing the number of steps required for a detection operation.

[0022]

Means for Solving the Problems In order to solve the above-mentioned problems, a solution taken by the invention of claim 1 is a magnetic field sensor, comprising a Hall element for outputting a voltage according to an applied magnetic field. , The voltage output from the Hall element is
A switch circuit that switches and outputs the polarities at opposite timings and the second timing, an amplifier that amplifies and outputs a voltage input from the switch circuit, and one end connected to one output terminal of the amplifier. A storage element that is connected and holds a voltage output from the amplifier; and a switch connected between the other output terminal of the amplifier and the other end of the storage element. ,
The switch is closed, and the voltage output from the amplifier is held in the storage element, and at the second timing, the switch is opened, the other output terminal of the amplifier, and the storage element of the storage element. The voltage between the other end is output.

Thus, with a simple circuit as described above,
Since the input offset voltage of the amplifier can be cancelled, it is not affected by the input offset voltage, and therefore, it is possible to configure an inexpensive magnetic field sensor with high accuracy, small variation between products, and small circuit scale. it can. Further, the strength of the magnetic field can be detected in the two steps of the first and second timings, so that the time required for the detection is short, and thus the power consumption can be reduced.

Here, the operation at the first timing is as follows:
The operation at the second timing may be performed repeatedly, or may be performed only once in response to an external request or the like. In addition, when it is performed repeatedly, the cycle, the ratio of the operation time of the timing,
The length of the period that does not belong to any operation period at any timing is not limited. For example, the same effect can be obtained even if the magnetic field sensor is operated intermittently at regular intervals. The invention according to claim 2 is the magnetic field sensor according to claim 1, wherein the switch circuit includes a first input storage element and a second input storage element, and at the first timing, While holding the voltage output from the Hall element in the first input storage element, and outputting the voltage held in the second input storage element to the amplifier, at the second timing, The voltage output from the Hall element is held in the second input storage element, and the voltage held in the first input storage element is output to the amplifier. I do.

Thus, after the voltage output from the Hall element is once held in the first or second input storage element, it can be input to the amplifier in a state separated from the Hall element. In this case, even if one end of the storage element is connected to an arbitrary potential, the voltage held in the storage element does not change, so that one of its input terminals has a predetermined potential or impedance with respect to the power supply as an amplifier. Can be used. (Specifically, for example,
The difference voltage between the two terminals of the Hall element can be converted into, for example, a voltage corresponding to the potential of one output terminal of the magnetic field sensor and input to an amplifier that amplifies the voltage corresponding to the potential of the one output terminal. In this case, the potential of the one output terminal may be a fixed reference potential (including ground).
The potential may not be the reference potential. An amplifier in which one of the input terminals has a predetermined potential with respect to the power supply or the like as described above, such as an operational amplifier, amplifies an input voltage and outputs either a non-inverted output voltage or an inverted output signal. Can be easily configured by forming a positive-phase amplifier circuit using a single-output type amplifier that outputs the same. Therefore, the single-output type amplifier as described above has a considerably smaller number of elements constituting the output section than the two-output type amplifier, so that the magnetic field sensor can be configured with a significantly smaller circuit scale and a smaller chip area. The invention according to claim 3 is the magnetic field sensor according to claim 1 or claim 2, wherein at least one of the storage element, the first input storage element, and the second input storage element. The one storage element is a capacitor.

By using a capacitor as a storage element as described above, a small-sized magnetic field sensor suitable for IC can be realized. The invention according to claim 4 is the magnetic field sensor according to any one of claims 1 to 3, wherein the switch,
And at least one of the switches constituting the switch circuit is configured by connecting a transistor having a first conductive property and a transistor having a second conductive property in parallel. 3, the first switch element is provided between one end and the other end of the switch, and both ends of the second switch element are both connected to one end of the first switch element. And both ends of the third switch element are connected to the first switch element.
Connected to the other end of the switch element, and the first
A transistor of the first conductivity characteristic of the switch element of
The second conductive transistor of the second and third switch elements and the second conductive transistor of the first switch element; the second and third transistors of the first switch element;
Wherein the transistor having the first conductive characteristic of the switch element is driven by binary signals having different logical values.

Thus, even when a switch having a MOS structure is used, for example, the parasitic capacitance between the gate and the source or between the gate and the drain or between the storage element and the storage element depends on the change in the voltage of the gate terminal for opening and closing the switch. Thus, a change in the voltage held in the storage element due to the movement of the electric charge is prevented, so that a more accurate magnetic field sensor can be configured. In addition, the invention of claim 5 is based on claim 1
The magnetic field sensor according to any one of claims 1 to 4, wherein at least one of resistors for determining a gain of the amplifier.
The individual elements are elements manufactured by the same method as the Hall element.

Thus, even when the resistance value of the Hall element is reduced due to, for example, a variation in manufacturing conditions, the resistance value of the resistor that determines the gain of the amplifier is also reduced, so that the output voltage of the Hall element is increased. Accordingly, the gain of the amplifier can be reduced correspondingly, so that a magnetic field sensor capable of performing highly accurate detection regardless of the variation of the Hall element or the resistance value can be configured.

Here, the same manufacturing method means that the Hall element and the voltage amplifier are formed on the same semiconductor chip, for example, through the same impurity diffusion step or the same N-well. Means that On the other hand, there is no particular difference in physical element size or shape. Therefore, if the Hall element and the resistor are elements manufactured by the same manufacturing process, the Hall element and the resistor are elements manufactured by the same manufacturing method even if the size or shape of the resistor differs. The invention according to claim 6 is a magnetic field sensor, wherein the Hall element outputs a voltage corresponding to an applied magnetic field, and the output voltage input from the Hall element is amplified and output to an amplifier output terminal pair. An amplifier, a capacitor having both ends connected to the amplifier output terminal pair, inserted between one of the amplifier output terminal pairs and one terminal of the capacitor, closed with a predetermined first signal and opened with a second signal; A switch unit, and an output terminal pair for individually outputting voltages at both ends of the switch unit,
It is characterized in that the polarity of the output voltage of the Hall element input to the amplifier is opposite to each other in the first signal period and the second signal period.

As a result, the input offset voltage of the amplifier can be canceled with a simple circuit as described in the first aspect. A small, small, and inexpensive magnetic field sensor can be realized. Claim 7
The present invention is a magnetic field sensor, wherein a Hall element that outputs a voltage according to an applied magnetic field to first and second terminal pairs, first and second capacitors, and the first terminal pair A first connection portion that connects each end of the first capacitor, a second connection portion that connects the second terminal pair and both ends of the second capacitor, and a first connection portion. A first switch portion which is inserted and connected, and the first connection portion is closed with a predetermined first signal and opened with a second signal; and the second connection portion which is inserted and connected to the second connection portion is connected to the second connection portion. A second switch unit that opens with a signal of 1 and closes with a second signal, an amplifier that amplifies a signal supplied to an input terminal and outputs the amplified signal to an output terminal, a first output terminal, and a first capacitor. One end and the input terminal of the amplifier, and the other end of the first capacitor and the first output. A third connecting portion for connecting each of the first and second terminals, a third connecting portion for connecting one end of the second capacitor and an input terminal of the amplifier, and a third connecting portion for connecting the other end of the second capacitor and the first output terminal. 4, a third switch portion inserted and connected to the third connection portion, the third connection portion being opened by the first signal and closed by the second signal, and the fourth connection portion. A fourth switch section that is inserted and connected, and closes the fourth connection section with the first signal and opens with the second signal;
A second output terminal, a third capacitor having one end connected to the output terminal of the amplifier and the other end connected to the second output terminal, and both ends individually connected to the first and second output terminals. A fifth switch unit connected to the first signal and closed by the second signal and opened by the second signal, wherein a signal is taken out between the first and second output terminals.

As a result, the input offset voltage of the amplifier can be canceled out with a simple circuit in the same manner as described in the first and second aspects. Thus, a small and inexpensive magnetic field sensor with little variation can be realized. Moreover,
With a simple circuit configuration, the difference voltage between the two terminals of the Hall element is converted into a voltage corresponding to the potential of one output terminal of the magnetic field sensor, and the voltage corresponding to the potential of one output terminal of the magnetic field sensor is input to the single output amplifier. Therefore, a single-output amplifier can be used as an amplifier for amplifying a voltage with respect to the potential of one output terminal of the magnetic field sensor, and a magnetic field sensor with a smaller circuit scale can be configured. Here, the potential of one output terminal of the magnetic field sensor may be a fixed reference potential, or may not be a fixed reference potential. The invention according to claim 8 is the magnetic field sensor according to claim 6, further comprising: comparing a voltage between the output terminal pair with a predetermined voltage, and outputting a comparison result as a binary signal. And a latch circuit that receives the binary signal and holds and outputs the binary signal in synchronization with a predetermined phase of the second signal.

As a result, the strength of the magnetic field is detected with high precision as described above, and an accurate comparison result based on this can be output. The invention of claim 9 is
8. The magnetic field sensor according to claim 7, further comprising: comparing a voltage between the first output terminal and the second output terminal with a predetermined voltage, and outputting a result of the comparison as a binary signal. And a latch circuit to which the binary signal is input and which holds and outputs the binary signal in synchronization with a predetermined phase of the second signal.

Thus, the strength of the magnetic field is detected with high precision as described above, and an accurate comparison result based on the detected strength can be output. Claim 10
The present invention is the magnetic field sensor according to claim 8 or 9, wherein the predetermined voltage of the comparator is configured to be different according to an output signal of the latch circuit.

With this, it is possible to provide the comparator with a hysteresis in the determination, and to output a stable signal in which chattering with respect to a noise signal is suppressed from the comparator. By providing this signal to the latch circuit, the determination accuracy can be improved. A high and stable signal can be output from the latch circuit. An invention according to claim 11 is a magnetic field sensor, wherein a Hall element that outputs a voltage corresponding to an applied magnetic field, and a voltage output from the Hall element is transmitted at a first timing and a second timing. A first switch circuit for switching and outputting the opposite polarity, an amplifier for amplifying and outputting the voltage input from the first switch circuit, and a storage element for holding the voltage output from the amplifier Connecting the output terminals of the amplifier and the storage element in parallel so that the voltage output from the amplifier is held in the storage element at the first timing, In the output terminal of the amplifier, the voltage output from the amplifier and the voltage held in the storage element are added so that the amplification components of the voltage input to the amplifier are added with the same polarity. Characterized in that the said storage device and a second switching circuit connected in series with the.

As a result, the voltage output from the Hall element is amplified and added with the same polarity, while the input offset voltage of the amplifier is added with the opposite polarity and cancels out. Thus, it is possible to detect a high-precision magnetic field in which the offset signal component included in the output of the magnetic field sensor is reduced. Further, since the strength of the magnetic field can be detected in the two steps of the first and second timings, the time required for the detection is short, and therefore, the power consumption can be reduced. According to a twelfth aspect of the present invention, in the magnetic field sensor of the eleventh aspect, the first switch circuit temporarily holds a voltage output from the Hall element and then disconnects the voltage from the Hall element. An output storage element for outputting is provided.

Thus, the voltage held in the storage element does not change even if one end of the storage element is connected to an arbitrary potential, and is held in the storage element in a state where the storage element is disconnected from the Hall element. Since the output voltage is output, an amplifier having one of its input terminals having a predetermined potential or impedance with respect to the power supply can be used. Further, such an amplifier can be easily configured by forming a positive-phase amplifier circuit using a single-output amplifier as described in claim 2, so that the circuit scale is significantly reduced. A magnetic field sensor can be configured with a small chip area.

[0037]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a circuit diagram showing an entire configuration of a magnetic field sensor according to Embodiment 1 of the present invention.
In the figure, 1 is a Hall element, 2 is a switch circuit, 3
Is a voltage amplifier, 4 is a capacitor (capacitor) as a storage element, and 5 is a switch. The Hall element 1 has 4
The terminals A, A ', BB, and B' are formed in a plate shape having a geometrically equivalent shape. The switch 5 and the switch circuit 2 are controlled by, for example, a phase signal output from a clock generation circuit (not shown). More specifically, the switch 5 closes in response to a pulse of the first phase in the first phase signal (a) shown in the timing chart of FIG. Further, the switch circuit 2 responds to the pulse of the first phase and the pulse of the second phase in the second phase signal (b), as described later, with a power supply and a voltage amplifier 3 (not shown), The connection between the terminals A, A ', B, and B' of the element 1 is switched. That is, this magnetic field sensor outputs a voltage corresponding to the strength of the magnetic field by the two-step operation of the first and second timings corresponding to the pulses of the first and second phases as described below. It has become.

First, at the first timing, the power supply voltage is applied between the terminals A and A 'of the Hall element 1 via the switch circuit 2 and the voltage Vh between the terminals BB and B' is Is input to Therefore, assuming that the voltage amplification factor of the voltage amplifier 3 is β, the voltage amplifier 3 outputs the sum of the voltage Vh between the terminals BB and the input offset voltage Voff of the voltage amplifier 3 as shown in the following equation (8). Is output. More specifically, the voltage of the non-inverting output terminal 3b (+) based on the inverting output terminal 3a (-) of the voltage amplifier 3 becomes V1.

V1 = β (Vh + Voff) (8) At this first timing, when the switch 5 is closed, the capacitor 4 is charged to the voltage V1. (The voltage of the terminal 4b based on the terminal 4a of the capacitor 4 becomes V1.) Next, at the second timing, the power is supplied between the terminals B and B 'of the Hall element 1 via the switch circuit 2. When the voltage is applied, the voltage −Vh ′ between the terminals A and A ′ is set to the voltage amplifier 30 so that the voltage −Vh ′ has a polarity opposite to that of the first timing.
Is input to Therefore, the voltage V2 shown in the following equation (9) is output from the voltage amplifier 30.

V2 = β (−Vh ′ + Voff) (9) That is, since the influence of the input offset voltage Voff is the same as the first timing regardless of the polarity of the input voltage, the output voltage V2 of the voltage amplifier 3 becomes the first voltage. Is a voltage proportional to the sum of the voltage −Vh ′ between the terminals A and A ′ having the opposite polarities and the input offset voltage Voff.

At the second timing, the switch 5 is opened, and the inverting output terminal 3a and the non-inverting output terminal 3b of the voltage amplifier 3 and the capacitor 4 are connected in series between the output terminals 6 and 7. State. At this time, since the charging voltage of the capacitor 4 does not change while being maintained at the output voltage V1 of the voltage amplifier 3 at the first timing, the voltage between the output terminals 6 and 7 (the output voltage of the magnetic field sensor)
V is the sum of the voltage V2 of the non-inverted output terminal 3b based on the inverted output terminal 3a of the voltage amplifier 3 and the voltage -V1 of the terminal 4a based on the terminal 4b of the capacitor 4, that is, As shown by the following equation (10), the voltage V1 is subtracted from the voltage V2.

V = V2−V1 = −β (Vh + Vh ′) (10) Accordingly, a voltage V in which the influence of the input offset voltage Voff is canceled is obtained as the output voltage of the magnetic field sensor. In addition, since the output voltages Vh and Vh ′ from the Hall element 61 at the first and second timings are added to the output voltage V, the prior art 1 described in US Pat.
As described in No. 7,150, the influence of the element offset voltage is also canceled.

As described above, the offset signal component (variation) included in the output of the magnetic field sensor is suppressed with a smaller circuit scale than the magnetic field sensors (FIGS. 7 and 9) described in the prior arts 1 and 2. And can detect the magnetic field with high accuracy.

In addition, the conventional magnetic field sensor of the prior art 3 requires three steps for one detection operation.
Since the magnetic field sensor according to the present embodiment requires only two steps, the time required for the detection operation is short. Therefore, for example, when the detection operation is performed once every fixed period, and when the power supply to the magnetic field sensor is stopped during each detection operation, the average power consumption can be reduced.

Since the charging of the capacitor 4 is not performed by the amplifier having the current output but by the voltage amplifier 3 having the voltage output, the variation in the output voltage due to the variation in the capacitance of the capacitor 4 can be reduced. (Embodiment 2) FIG. 3 is a circuit diagram showing an overall configuration of a magnetic field sensor according to Embodiment 2 of the present invention. In the following embodiments, components having the same functions as those in the first embodiment and the like will be assigned the same reference numerals and descriptions thereof will be omitted.

In the figure, reference numeral 20 denotes a switch circuit;
Is a voltage amplifier.

The switch circuit 20 includes switches 5...
8 and a capacitor (capacitor) as a storage element 9.
10 are provided. Each of the above switches 5
And the switch 5 connected to the capacitor 4 in the same manner as in the first embodiment closes in response to the pulse of the first phase in the first phase signal (a) shown in the timing chart of FIG. The switches 8 are closed in response to a pulse of the second phase in the second phase signal (b). The switch circuit 20 is further provided with a switch for connecting a power supply (not shown) to the Hall element 1 in accordance with the first and second phase pulses. Since the same switch circuit as that of the first embodiment or a conventionally known switch circuit can be applied, the description is omitted.

The voltage amplifier 30 has the same function as that of the voltage amplifier 3 of the first embodiment in that it outputs a voltage proportional to the input voltage. For example, a differential input such as an operational amplifier is used. And a single-output high-gain amplifier 31 and two resistors 22 and 23 for determining an amplification factor (feedback amount). One of the input terminals is common to one of the output terminals, and the output of the magnetic field sensor is The terminal 6 is common (common terminal 30a), and the common terminal 30a is not high impedance with respect to the power supply. The reason why such a voltage amplifier 30 can be used will be described later.

This magnetic field sensor repeats the two-step operation of the first and second timings corresponding to the first and second phase pulses as follows,
A voltage corresponding to the strength of the magnetic field is output.

First, at the first timing, a power supply voltage is applied between the terminals A and A 'of the Hall element 1 via a switch (not shown) of the switch circuit 2. At this time, the voltage Vh generated between the terminals B and B ′ of the Hall element 1 is applied to the capacitor 9 by closing the switches 5.5 connected to the capacitor 9, and the capacitor 9 is charged. Also, switches 5.5 connected to the capacitor 10
Is closed, the voltage −Vh held in the capacitor 10 is input to the voltage amplifier 30 at the second preceding timing. (More specifically, the capacitor 10
Are connected to the common terminal 30a and the non-inverting input terminal (+) of the high gain amplifier 31 via the switches 5.5. Therefore, the voltage amplifier 30 outputs the second signal of the first embodiment.
Similarly to the timing (Equation (9)), the voltage V2 (the voltage of the output terminal 30b based on the common terminal 30a) shown in the following equation (11) is output, and the switch connected to the capacitor 4 When 5 is closed, the capacitor 4 is charged to this voltage V2.

V2 = β (−Vh ′ + Voff) (11) Next, at the second timing, the voltage −Vh ′ between the terminals A and A ′ is passed through a switch (not shown) of the switch circuit 2.
Has a polarity opposite to that of the voltage Vh between the terminals BB at the first timing.
A power supply voltage is applied between B '. The terminal A at this time
The voltage −Vh ′ between A ′ is changed by closing the switches 8.8 connected to the capacitor 10.
To charge the capacitor 10 (this voltage −
Vh ′ is input to the voltage amplifier 30 at the next first timing as described above. ). When the switches 8.8 connected to the capacitor 9 are closed,
The voltage Vh held in the capacitor 9 is input to the voltage amplifier 30 at the first timing. Therefore, the voltage amplifier 30 outputs the voltage V1 shown in the following equation (12) in the same manner as the first timing (Equation (8)) in the first embodiment.
Is output.

V1 = β (Vh + Voff) (12) At this second timing, the switch 5 connected to the capacitor 4 opens, and the common terminal 30a of the voltage amplifier 3 and the output The terminal 30b and the capacitor 4 are connected in series. At this time,
Since the charging voltage of the capacitor 4 remains unchanged at the output voltage V2 of the voltage amplifier 3 at the first timing, the voltage between the output terminals 6 and 7 (the output voltage of the magnetic field sensor) V 30, the sum of the voltage V1 of the output terminal 30b with reference to the common terminal 30a and the voltage -V2 of the terminal 4a with reference to the terminal 4b of the capacitor 4, that is, as shown in the following equation (13). And the voltage V2 is subtracted from the voltage V1.

V = V1−V2 = β (Vh + Vh ′) (13) As described above, similarly to the first embodiment, the offset signal component included in the output of the magnetic field sensor is suppressed to obtain a highly accurate magnetic field. Can be detected. In the magnetic field sensor according to the second embodiment, three steps of the second, first, and second timings are required to perform the detection operation only once, but the detection operation is performed a plurality of times. In such a case, the first and second timings need only be repeated, so that the number of steps required for one detection operation can be made close to two steps.

The voltage amplifier 3 is constituted by using a single-output high-gain amplifier 31 with a differential input, and such a high-gain amplifier 31 is provided as described in the above-mentioned prior art and the first embodiment. Compared to a simple two-output amplifier, the number of elements constituting the output section is considerably smaller, so that the magnetic field sensor can be configured with a significantly smaller circuit scale. Hereinafter, the reason why the voltage amplifier 3 can be configured using the single-output high-gain amplifier 31 with the above-described differential input will be described.

For example, when a power supply voltage is applied to the terminals A and A 'of the Hall element 1, the potentials of the terminals BB and B' have a certain potential difference from the reference potential of the power supply. Therefore, when the terminals B and B 'are connected to the two input terminals of the amplifier, both of the input terminals need to have a high impedance with respect to the power supply, that is, a floating potential with respect to the reference potential of the power supply. There is. Further, in order to perform highly accurate detection, the amplifier needs to have a certain accurate amplification factor. In order to satisfy the above conditions, it is necessary to use a two-output amplifier as described in the related art or the first embodiment.

On the other hand, in the magnetic field sensor of the present embodiment, for example, the terminal B of the Hall element 1 is set at the first timing.
After applying the voltage Vh between B 'to the capacitor 9 to accumulate electric charge and charge the capacitor 9 so that the voltage between both terminals becomes Vh, the capacitor 9 is connected to the Hall element 1 at the second timing.
And is connected to 30. In this case, the voltage between both terminals of the capacitor 9 does not change no matter what potential is connected to one terminal unless there is inflow and outflow of electric charge. Can be connected to therefore,
As the amplifier, it is possible to use a single-input amplifier in which one input terminal has a certain potential difference (a certain impedance) with respect to a reference potential of a power supply or the like. Such an amplifier is formed, for example, by forming a positive-phase amplifier circuit using a high-gain amplifier 31 having a small circuit scale of a single input and a differential input like the voltage amplifier 3 (in this case, The voltage amplifier 3 itself also has a single output), and can be easily configured. Therefore, a highly accurate magnetic field sensor with a smaller circuit scale than the magnetic field sensor of the first embodiment can be configured. Further, as a simple example in principle with respect to the potential of the input terminal as described above, for example, it is conceivable to use a drain-grounded FET and use the gate and the ground as input terminals. However, consideration must be given to accurately keep the amplification factor constant.

Since the potential of the common terminal 30a may be an arbitrary potential as described above, the potential may be, for example, a reference potential of a fixed voltage or a potential having a predetermined potential difference from the reference potential. The present invention can also use a single output amplifier in a magnetic field sensor in which the potential of the minus output terminal is not a constant reference potential (including ground).

The switch 5 may be provided between the output terminal 30b and the terminal 4b, and both ends of the switch 5 may be output terminals. (Embodiment 3) FIG. 4 is a circuit diagram showing an overall configuration of a magnetic field sensor according to Embodiment 3 of the present invention. This magnetic field sensor further includes a comparator 13 and a latch circuit 14 in addition to the configuration of the first embodiment, and a binary digitil of 0 or 1 (for example, low level or high level) according to the strength of the magnetic field. It is configured to output a signal.

In FIG. 4, 1 to 7 are the same as in the first embodiment. Reference numeral 13 denotes a comparator, 14 denotes a latch circuit, 15 denotes a clock generation circuit, 16 denotes a first phase clock generation circuit, and 17 denotes a second phase clock generation circuit. The comparator 13 compares a voltage output between the output terminals 6 and 7 with a predetermined reference voltage and outputs a binary digital signal. The latch circuit 14 holds the output from the comparator 13 at the time when the pulse of the second phase falls. Further, the first phase clock generation circuit 16 and the second phase clock generation circuit 17
Are the first and second described in Embodiment 1 (FIG. 2), respectively.
It outputs first and second phase signals (a) and (b) having pulses of the second phase.

The operation of the magnetic field sensor configured as described above will be described below. In this description, it is assumed that a constant magnetic field penetrates the Hall element 1 and the output voltage of the Hall element is constant without considering the offset. In the following operation, the operation until the voltage corresponding to the strength of the magnetic field is output from the output terminals 6 and 7 is the same as that described in the first embodiment. That is, first, a clock for determining the first phase (timing) is generated by the first phase clock generation circuit 16, and in response to this clock, between two terminals on one diagonal line of the Hall element 1 A power supply voltage is applied, and a Hall element output voltage proportional to the strength of the magnetic field is generated between the two terminals on the other diagonal line. The switch circuit 2 operates so that the output voltage is applied to two input terminals of the voltage amplifier 3. Therefore, a voltage proportional to the output voltage of the Hall element 1 is output from the voltage amplifier 3 and applied to the capacitor 4 via the switch 5 controlled by the first phase clock generation circuit 16, and the electric charge is stored in the capacitor 4. Stored. When the first phase ends, the switch 5 opens, and the output voltage of the voltage amplifier 3 in the first phase is held in the capacitor 4.

Next, a clock for determining the second phase is generated by the second phase clock generation circuit 17, and in response to this clock, the Hall element 1 outputs the Hall element output at the time of the first phase. A power supply voltage is applied between the two terminals on the other diagonal line where the voltage is generated, and the voltage between the two terminals on the one diagonal line is input to the voltage amplifier 3. Here, the switch circuit 2 switches so that the positive and negative polarities of the Hall element output voltage input from the Hall element 1 to the voltage amplifier 3 are opposite to those of the first phase. Therefore, the component of the output voltage of the voltage amplifier 3 corresponding to the output voltage from the Hall element 1 also has a polarity opposite to that of the first phase. At this time, since the switch 5 is opened, the voltage amplifier 3 stored in the capacitor 4 is opened.
Of the output voltage in the first phase and the output voltage in the second phase of the voltage amplifier 3 (difference depending on how to take the reference of the voltage), that is, the voltage minus the input offset voltage Voff− 2βVh is the voltage between the output terminals 6 and 7.

Therefore, the voltage between the output terminals 6 and 7 is input between the input terminals of the comparator 13. In the comparator 13,
The input voltage is compared with a predetermined reference voltage set in advance, and the comparison result (a digital signal of 0 (for example, low level) when the input voltage is lower than the reference voltage, and a digital signal of 1 (for example, high Level) is output from the output terminal of the comparator 13.

The latch circuit 14 receives the result of the comparison and the second phase signal (b) from the second phase clock generation circuit 17 to input the second phase signal (b). The input voltage (comparison result) is set to be latched at the timing when the pulse of the phase falls). Therefore, the latched constant value (a digital value of 0 or 1) is output from the output terminal 18 of the latch circuit 14 until the end of the next second phase.

In order to prevent chattering, it is preferable that the output value from the output terminal 18 is fed back to the comparator 13 to change the reference voltage so that the judgment has a hysteresis.

In the above example, an example is shown in which the comparator 13 and the latch circuit 14 are further provided in the configuration of the first embodiment. However, the present invention is not limited to this. The container 13 and the like may be provided. (Detailed Example of Switches Constituting Magnetic Field Sensor) In the magnetic field sensors according to the above-described embodiments, in order to perform more accurate detection, the switches 5 and 8 that are provided with a feed-through countermeasure may be used. preferable. That is,
For example, the switches 5.8 are configured by using bidirectional switch elements having a MOS-structure transistor whose gate is supplied with a binary voltage corresponding to the phase signals (a) and (b) as described above and whose opening and closing are controlled. In this case, when the voltage at the gate terminal of the transistor is changed to open and close the switches 5.8, the parasitic capacitance between the gate and the source or between the gate and the drain, and the capacitance connected to the switches 5.8 When the transfer of electric charge occurs between 4.9.9,
The voltage between both terminals of the capacitor may fluctuate.
Such a voltage change is caused by the switch 5 shown in FIG.
-By using 8, it is possible to reliably prevent this. That is, in FIG.
Are configured such that N-channel and P-channel MOS transistors are connected in parallel, and are driven by applying a binary voltage to the gate of each transistor. (Here, the parasitic capacitance of the switch element 50 is set, for example, to be equal to the sum of the parasitic capacitances of the switch elements 51 and 52.) The input / output terminals 50a and 50b of the switch element 50 5.8 are connected to the connection terminals 5a and 5b,
The connection between them is established. The switch element 51 has its input / output terminals 51a and 51b both connected to the input / output terminal 50a of the switch element 50, while the switch element 52 has its input / output terminals 52a and 52b both connected to the input / output terminal of the switch element 50. Connected to terminal 50b. The switch element 50 and the switch elements 51 and 52
Means that each of the phase signals (a) and (b) is controlled by two mutually opposite logic voltages output via one or two inverters. More specifically, for example, when a high-level voltage is applied to the gate of the N-channel transistor and a low-level voltage is applied to the gates of the P-channel transistors in the switch element 50, a low-level voltage is applied to the gates of the N-channel transistors in the switch elements 51 and 52. , A high-level voltage is applied to the gate of the P-channel transistor. Therefore, the direction in which the charge moves due to the parasitic capacitance of the switch element 50 and the direction in which the charge moves due to the parasitic capacitance of the switch elements 51 and 52 are opposite to each other, so that the movement of the charge is canceled. Therefore, voltage fluctuation due to movement of electric charge between the capacitor 9 and the like is reliably prevented. (Detailed Examples of Resistances Constituting Magnetic Field Sensor) In the magnetic field sensors of the above embodiments, in order to perform more accurate detection, at least one of the resistances that determine the gain (amplification factor) of the voltage amplifiers 3 and 30 is required. It is preferable that one predetermined resistor is formed by the same manufacturing method as that of the Hall element 1, that is, the same material and the same manufacturing process. That is, for example, taking the magnetic field sensor of the second embodiment (FIG. 3) as an example, when the Hall element 1 and the voltage amplifier 30 are formed on the same semiconductor chip, generally, the resistance value of the Hall element 1 is The resistance value of 23 also varies due to variations in constituent materials and manufacturing conditions. When the resistance value of the Hall element 1 is small, the output voltage of the Hall element 1 increases. On the other hand, of the resistors 22 and 23, when the resistance value of the resistor 22 inserted between the output terminal of the high gain amplifier 31 and the inverted (minus) input terminal is small,
The gain of the voltage amplifier 30 increases. Therefore, if the Hall element 1 and the resistor 22 are formed by using the same material and the same manufacturing process, more specifically, for example, an N-type impurity is diffused into a P-type semiconductor substrate to form the Hall element 1 and the resistor 22, If the resistance value of the Hall element 1 is small when the resistance value of the Hall element 1 is small, the output voltage of the resistance element 23 is high. Is also reduced, the gain of the voltage amplifier 30 is reduced. Conversely, when the resistance value of the Hall element 1 is large, its output voltage is low, but the resistance value of the resistor 22 is also large, so that the gain of the voltage amplifier 30 is large.
Therefore, the effect of the variation in the resistance value of the Hall element 1 and the effect of the variation in the resistor 22 cancel each other, so that an output voltage with a small variation can be obtained from the output terminals 6 and 7.

[0067]

According to the present invention, the input offset voltage of the amplifier can be canceled with a simple circuit. This allows
There is an advantageous effect that an output with little variation can be obtained without being affected by the input offset voltage, and a small-sized and inexpensive magnetic field sensor can be realized.

According to the present invention, the number of steps is small,
That is, since the magnetic field can be detected in a short time, an advantageous effect that a low power consumption magnetic field sensor can be realized can be obtained.

Further, according to the present invention, it is possible to convert an output signal of the differential voltage of the Hall element into a voltage with respect to a reference potential or the like, and to input the voltage with respect to the reference potential or the like to a single output amplifier with a simple circuit. it can. Accordingly, it is possible to realize a magnetic field sensor that amplifies the output signal of the differential voltage of the Hall element by a single-output amplifier having a simple circuit of an output unit and a small chip area. Therefore, an advantageous effect that a smaller and less expensive magnetic field sensor can be realized is obtained.

Further, according to the present invention, there is obtained an advantageous effect that it is possible to realize a magnetic field sensor capable of minimizing the variation in the output voltage regardless of the variation in the resistance value of the Hall element.

Further, according to the present invention, it is possible to realize a magnetic field sensor using a storage element which is small and is suitable for IC. Thus, an advantageous effect that a small and inexpensive magnetic field sensor can be realized can be obtained.

Further, according to the present invention, there is obtained an advantageous effect that it is possible to realize a magnetic field sensor in which variation in output voltage due to variation in capacitance of a capacitor is small.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic field sensor according to a first embodiment of the present invention.

FIG. 2 is a timing chart according to the first to third embodiments of the present invention.

FIG. 3 is a configuration diagram of a magnetic field sensor according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a magnetic field sensor according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a switch of the magnetic field sensor of the present invention.

FIG. 6 is a configuration diagram of a magnetic field sensor according to Conventional Technique 1.

FIG. 7 is a configuration diagram of a magnetic field sensor according to the related art 2.

FIG. 8 is a timing chart of Conventional Technique 2.

FIG. 9 is a configuration diagram of a magnetic field sensor according to Conventional Technique 3.

FIG. 10 is a timing chart of the conventional technique 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hall element 2 Switch circuit 3 Voltage amplifier 3a Inverted output terminal 3b Non-inverted output terminal 4 Capacitor 4a terminal 4b terminal 5 Switch 5a / 5b Connection terminal 6.7 Output terminal 8 Switch 9 Capacitor 10 Capacitor 13 Comparator 14 Latch circuit 16th 1 phase clock generation circuit 17 second phase clock generation circuit 18 output terminal 20 switch circuit 22 resistor 23 resistance 30 voltage amplifier 30a common terminal 30b output terminal 31 high gain amplifier 50-52 switch element 50a / 50b input / output terminal 51a / 51b input / output terminal 52a / 52b input / output terminal

Claims (12)

[Claims] A hall element for outputting a voltage corresponding to an applied magnetic field; and a voltage output from the hall element being switched so as to have opposite polarities at a first timing and a second timing. A switch circuit that amplifies and outputs a voltage input from the switch circuit; a storage element having one end connected to one output terminal of the amplifier and holding a voltage output from the amplifier; A switch connected between the other output terminal of the amplifier and the other end of the storage element, wherein the switch is closed at the first timing, and the voltage output from the amplifier is stored in the storage element. On the other hand, at the second timing, the switch is opened to output a voltage between the other output terminal of the amplifier and the other end of the storage element. Magnetic field sensor, characterized in that configured. 2. The magnetic field sensor according to claim 1, wherein the switch circuit includes a first input storage element and a second input storage element, and the switch circuit outputs the first input storage element and the second input storage element at the first timing. While the output voltage is held in the first input storage element, the voltage held in the second input storage element is output to the amplifier, and at the second timing, the voltage is output from the Hall element. A magnetic field sensor, wherein the output voltage is held in the second input storage element, and the voltage held in the first input storage element is output to the amplifier. 3. The magnetic field sensor according to claim 1, wherein at least one of the storage element, the first input storage element, and the second input storage element is provided. A magnetic field sensor, wherein the storage element is a capacitor. 4. The magnetic field sensor according to claim 1, wherein at least one of the switch and a switch constituting the switch circuit are each a transistor having a first conductive characteristic. A first, a second, and a third switch element configured to be connected in parallel with a transistor having a second conductive characteristic, wherein the first switch element is connected between one end and the other end of the switch. Both ends of the second switch element are both connected to one end of the first switch element, and both ends of the third switch element are both connected to the other end of the first switch element. Being connected, the transistor having the first conductive property of the first switch element, the transistor having the second conductive property of the second and third switch elements, and the first switch And the second conductive transistor of the second switching element and the transistor of the first conductive characteristic of the second and third switch elements are driven by binary signals having different logic values from each other. A magnetic field sensor characterized in that: 5. The magnetic field sensor according to claim 1, wherein at least one of the resistors for determining the gain of the amplifier is an element manufactured in the same manner as the Hall element. A magnetic field sensor comprising: 6. A Hall element for outputting a voltage corresponding to an applied magnetic field, an amplifier for amplifying an output voltage input from the Hall element and outputting the amplified output voltage to an amplifier output terminal pair, and both ends of the amplifier output terminal pair. A switch connected between one of the amplifier output terminal pair and one terminal of the capacitor, and closed by a predetermined first signal and opened by a second signal; and a voltage across the switch. And an output terminal pair for individually outputting the output signals of the Hall elements, and the polarities of the output voltages of the Hall elements input to the amplifier are opposite to each other in the first signal period and the second signal period. A magnetic field sensor comprising: 7. A Hall element for outputting a voltage corresponding to an applied magnetic field to first and second terminal pairs, first and second capacitors, the first terminal pair and the first capacitor. A first connecting portion for connecting both ends, a second connecting portion for connecting the second terminal pair and both ends of the second capacitor, and a second connecting portion which is inserted and connected to the first connecting portion. A first switch unit that closes one connection unit with a predetermined first signal and opens with a second signal; and a second switch unit that is inserted and connected to the second connection unit and opens the second connection unit with the first signal. A second switch unit that closes with a second signal, an amplifier that amplifies a signal supplied to an input terminal and outputs the amplified signal to an output terminal, a first output terminal, one end of the first capacitor, and an output terminal of the amplifier. An input terminal, and the other end of the first capacitor and the first output terminal. A third connection portion for connecting; a fourth connection portion for connecting one end of the second capacitor and an input terminal of the amplifier; and a second connection portion for connecting the other end of the second capacitor and the first output terminal, respectively. A third switch portion inserted and connected to the third connection portion and opening the third connection portion with the first signal and closing the second connection portion with the second signal; and a third switch portion inserted and connected to the fourth connection portion. A fourth switch section that closes a fourth connection section with the first signal and opens with a second signal, a second output terminal, and one end connected to the output terminal of the amplifier and the second output terminal. A third capacitor having the other end connected thereto, and a fifth switch unit having both ends individually connected to the first and second output terminals and closed with the first signal and opened with a second signal, A magnetic field sensor for extracting a signal between the first and second output terminals. 8. The magnetic field sensor according to claim 6, further comprising: a comparator for comparing a voltage between the pair of output terminals with a predetermined voltage, and outputting a comparison result as a binary signal; A latch circuit that receives a value signal, and holds and outputs the binary signal in synchronization with a predetermined phase of the second signal. 9. The magnetic field sensor according to claim 7, further comprising: comparing a voltage between the first output terminal and the second output terminal with a predetermined voltage; A comparator that outputs the signal as a signal; and a latch circuit that receives the binary signal, holds and outputs the binary signal in synchronization with a predetermined phase of the second signal. Magnetic field sensor. 10. The magnetic field sensor according to claim 8, wherein the predetermined voltage of the comparator is configured to be different according to an output signal of the latch circuit. Sensor. 11. A Hall element for outputting a voltage corresponding to an applied magnetic field, and switching a voltage output from the Hall element so that the polarity is reversed between a first timing and a second timing. A first switch circuit, an amplifier for amplifying and outputting a voltage input from the first switch circuit, a storage element for holding a voltage output from the amplifier, While the output terminal of the amplifier and the storage element are connected in parallel so that the voltage output from the amplifier is held in the storage element, the voltage output from the amplifier at the second timing is The voltage held in the storage element is connected in series between the output terminals of the amplifier and the storage element such that the amplified components of the voltage input to the amplifier are added with the same polarity. A magnetic field sensor comprising: 12. The magnetic field sensor according to claim 11, wherein the first switch circuit temporarily holds a voltage output from the Hall element,
A magnetic field sensor comprising: an input storage element that outputs data in a state separated from the Hall element.